sign in sign up
<<
Home , Iphigenia (plant), Monocotyledon, Strelitzia nicolai

UNIT 23 - MONOCOT FAMILIES

Structure

I~itroduction 0b.jectives Lil iaceae Summary Terminal Questio~is Answers

23.1 INTRODUCTION The non no constitute one of the two major groups of angiosper~ns. They are rnostly lierbaceo~isplants. Tlie stems liave closed vascular bundles. Due to the absence of vasc~~larca~nbium, tliese do not exhibit normal as observed in tlie dicotyledo~iswliicli you have already read in Unit 8 of Block I1 of Develop~iientalBiology, LSE-06. T-lowever, a few are woody and have -like stems je.g., barnboos and palms). The generally liave a sheath and sliow parallel venation. Tlie liave a cliaracteristic trinierol~sorganisation. Tlie enibryo rarely sliows differentiation and lias a single (hence the lialiie mono) . 'l'lie e~idospertiiis ~~sually abundant.

Tlie monocotyledons are comparatively fewer tlian the . TIiey are classified into 7 series and 34 families in 13entliarn and Hooker's classification. In this system, tlie ~nonocotyledo~isare classified after tlie dicotyledons. In contrast to tliis, they are classified before the dicotyledo~isin Engler & Prantl's System. A total of 1 1 orders and 34 fa~iiiliesare recognised in tliis system. Taklitajan in his system of classification (as revised in 1997) has classified tlie mo~iocotyledonsin . This is placed after class Mag~ioliopsida(= dicotyledons), l'he Liliopsida is divided into 6 subclasses, 16 super orders, 57 orders and 13 1 families.

In this unit yo11 will study about the characters of 4 important monocot families. These are Musaceae, , Arecaceae (Palmae) and Poaceae (Grarnineae). l'liis study follows tlie same pattern as in tlie case of tlie families dealt with in ~uiits2 1 arid 22.

Objectives AAer studying 1:Iiis unit, you should be able to:

@ know about the families Musaceae, Liliaceae, Arecaceae and Poaceae. remember tlie ~iolnenclaturaltype of each name. @ know about tlie size, distributio~ias well as tlie number of genera and of tliese families foulid in India. @ understand the morphological diversity in eacli family. list tlie diagnostic features of eacli fa~nilya~id recognise tlie plants in the field.

@ classify each family in 3 systerns of classification and know its systematic position.

@ list the eco~io~nicallyi~nportatit platits and know about their uses. The family Nomenclatural : Musn

Gerieral Information This is a ve~ys~nall family of ~nonocotyledono~~splants. Tliere are two views on tlie number of genera and species in this family. Engler and Prantl classified 6 genera in this family. Tliese are (about 80 species incliiding ); (25 species); (4 species); Heliconirr (30 species); Lowia (2 species); and (2 species).

On the other hand, taxonomists like Taklitajan, Hutcliiriso~iand C~~onquist recognise only 2 genera - Mtrsa (about 60 species) and Ensetc (about 20 species). ?'lie other genera are classified in (Raverzala and Strelitzia);

Heliconiaceae (genus ) or Lowiaceae (Orchidantha including Lowia). ' This difference in the size of tho famiiy Musaceae in different systems of classification is mainly due to the morphological diversity amongst tlie plants. Therefore, it would be more appropriate to know about this diversity and follow tlie suggestion of Engler & Prantl.

In this context of tlie family Musaceae you should remember two terms; strict0 and sensu lato. These were introduced to you in LSE-07, Block 2, Unit 7. Therefore, the following discussion describes tlie fa~niIyMusaceae sensu lato,

Tlie members of this family are tropical in distribution. They are found in Asia, Africa and South America. However, there is a large-scale cultivatio~iof tlie economically important genus Musa throughout tlie warmer parts of tlie world. Ravenala, Strelitzin and Helicoiiia are cultivated in parks and gardens as ornamentals.

Ficld Recognition Herbaceous perennials with "tree like" pseudoste~iisor woody palm-like plants; leaves large with oblong blade having a distinct slieatli, a stout midrib and parallel venation; illflorescence with characteristic spathe-like ; flowers zygomorphic and generally unisexual; male flowers usually with five and one ; female flowers with tricarpellary gynoeciu~nand inferior ovary.

Morphological Diversity The plants of the family Musaceae are generally perennial herbs with an underground rliizome. In the largest genus Musa, an aerial pseudostein (growing up to a height of 5 meters) is formed. This is actually made up of large stiff slieaths which are rolled around ane another. "Tllerefore, it is not a true stem. The true stem is the underground rl~izorne,the apex of which is present at tlie base of the pseudostem. The rhizomatous stern grows out tlirough the cylindrical pseudostelm to bear the terminal . Tlie plants are herbaceous perennials in Lowia, Orchidantha and (called Bird of Paradise) also. But and Ravenala madagascarie~sis(cal led Traveller's tree of Madagascar), are tall woody with a palm-like appearance,

Leaf: In Musa, tlie leaves are arranged radially in two rows on tlie riiizome. This pattern of leaf arrangement also occurs in the other herbaceous perennials. In Musu, the leaves appear to arise at the apex of tlie pseudostem (Fig. 23.1). T11is is due to th'e fact that the leaf sheaths are rolled around one another and each new leaf pushes up 1 its convolute blade through the pseudostern. The large blade then expands above the, older leaves. In the woody plants like Rmenala, the leaves are arranged in two rows, forming a crowded crow11 at the apex of the (Fig. 23.2). . I I Monocot Families

Fig. 23.1: Musn sp. a) Young . b) nese of olrnt with s~~cket~.c) Inflorcsccncc. d) Pcmnlc flowers and . c) Mnlc flowcrs and brrct. f) Felnnlc . g) Fcnlnle flower wit11 pcrinntll opcnecl. 11) Fcmale flower ill longitl~dinrlscction. i) blz~lcIlowcr. j) ~III~Cflowcr wit11 pcrianth opcncd. k) Mnle flower ie longitudinal section. I) Fruit bunch Families of Angiosperms

Fig. 23.2: R~venalamadogascoriensis.a) Plant in flowering stnge. b) Open flower. c) Opening cnpsule. . ' dl with aril. The leaves are large and consist of a strong sheath wliicl~is separated from tlie oval or oblong blade. The blade has a thick midrib from which numerous parallel veins travel to the margins. There is no a~lastomosisof the seco~idaryveins (common in dicots), so that the edges of the large blade easily split. Mature leaves are generally torn up to the midrib thus offering very little resistance to wind forces. In Ravenala rnadagascnriensis (Traveller's tree), water accunlulates in the leaf base. This water has been used for drinlting purposes by travellers.

Inflorescence: The infloresce~lceis terminal in Musn: It is a large racemose inflorescence having numerous large bracts. The bracts are spathe-like and brightly coloured. Each bract encloses a large number of unisexual flowers. The flowers towards the apex of the inflorescence are male, while those towards the base are female. Sometimes bisexual flowers may be present in the middle region of the inflorescence. In Heliconia (Fig. 23.3) the ter~ni~ialinflorescence has 2 rows of large bracts. In the axil of each bract, there is a rnonochasial cyme of the cincinnus type. Ravenala and Sfrelitzia have several axilliary i~iflorescenceswith large bracts. Each bract has a cincin~lustype of tnonocliasial cyme with many (Ravenala) or few (Strelitzia)flowers. In Lowia and Orchidantha, the inflorescence is a panicle with large orchid-like flowers.

Flower: The flowers are bracteate, zygomorphic and bisexual in their ontogeny, They become unisexual because either the androeciuni 01- the gynoeciu~ndoes not mature. They are trimerous as in other monocotyledo~lsand they are epigynous. The of the flower consists of two trimerous wllorls and the six arc generally petaloid. The perianth may also be distinguished into a distinct calyx and corolla. In Musa, the 3 outer and 2 inner tepals are united to form a tube, while the sixth is free. They are unequal in size and the inner tepals are smaller and narrower than the outer. In Ravenala, tlie 2 whorls of the periantli show a differentiation into a calyx and corolla. One (median) is slightly smaller than all other segments of the perianth. Strelitzia has free while 2 lateral +t?l~ are w;iidd to form a lar e broadly winged arrow shaped structure which Monocot Families surrounds the stamens. The 3' 9 or odd petal is very short and broad. In Lowia and

Orchidantha (Fig. 23.4), the sepals are unitedhto a cup-like structure. The two L. lateral are small while the third forms a large spreading labellum. In these genera, the flowers show resupination (this is a change in the orientation of the flower caused by a twist in some portion of the flower axis. This results in the posterior portion of the flower to appear anterior and vice-versa). This is a com~nonfeature in the family .

Fig. 23.3: Heliconinsolomonensb.a) Inflorescence, notc pollinntlng ~nncroglossinehat. b) Clncinnnl bract cut away to sl~owflower at anthcsis. c) Ovary wlth style, , and staminode. d) Stnminode. e) Pyrenes in ventral and lateral view.

Androecium: There are two trimerous whorls of stamens in each flower. All six .stamens are fertile and of equal size in Ravenala. In some species of Musa (e.g., M ensete), 5 stamens are large and tlie sixth one and is small, but in all the other genera, only 5 stamens are fertile and the sixth is reduced to a starninode. This staminode becomes petaloid in Heliconin and it is completely suppressed in Lowia and Orchidantha. The anthers are linear, dithecous and show introrse dehiscence. A rudimentary ovary which is generally modified into a nectary is usually present in the male flowers.

Gynoecium: The is tricarpellary, syncarpous, with an inferior ovary. The ovary is trilocular and the is axile. There are I-a: ovules in each locule. is secreted in septa1 glands. The style is simple and the stigma is more-or less 3-lobed or capitate. The stamens generally do not develop in the female flowers.

Sometimes in Musa, both androecium and gynoecium show normal development and the flowers become bisexual. Families of Angiosperms

Fig. 23.4: Orchldanlha longiflafa.a) Habit. b) Androeci~~mand stigma, rbsxlal view. c) Style and stigmatic lobes, d, e) 0.nmrill~rloides Flowers and habit. e) Arillate seed.

Fruit: Different kinds of fruit aie produced in ~llernbersof this family. In Musa, the fruit is a fleshy berry. In Heliconia,'it is a schizocarp which opens into 3 one-seeded portions. A develops in Ravenala, Strelitzia, Lowia and Or~clzidantha.This capsule is trilocular and opens loculicidaily. In the cultivated edible forms ofMusa, are not produced. These are mostly triploid hybrids. But in the wild and naturally occurring species of Mzrsa, numerous seeds are produced. These seeds are embedded in the fleshy pulp. In Musa msete, the fruit' is dry and al~noslleathery. In Ravenala, the seeds are arillate. The aril is shield- i like with firnbriatc edges and it is brightly coloured. Arillate seeds also occur in ! Strelitzia, Lowia and Orchidantha. In Heliconin no aril is produced. The seeds I have a hard and thick testa and a straight ernbryo. A uutritive called i perisperm is present. This is made up of a part of tlie nucellus, containing resew4

food material, and the . It is used by the nt tlie lime of iI . I i Diagnostic Features of the Family I 1. Monocotyledonous plants, I 2. Herbaceous perennials with tree-like pseudostenls or woody palm-like plants. ! 3. Leaves large with a strong sheath, oblong blade, a stout midrib and parallel ; venation, I 4. Inflorescence with cllaracteristic spathe-like bracts. Monocot Families 5. Flowers zygomorpllic and generally u~~isexual. 6. Stamens generally 5. 7. Tricarpellary gynoecium with inferior ovary. 8. Placentation axile. 9. Fruit a berry or a capsule. 10. Seeds with hard thick testa wit11 or without an aril. I 1. Perisperm present.

Systematic Position The family Musaceue is not recognised as a separate family in Benthani and Hooker's classification. Tliis group of plauts is classified as a tribe Musaeae in tile and this'is classified in series 11 Epigynae. In Engler & Prantl's classification, the family Mi~saceaeis recognised as a distinct family. It is classified in Scitamineae. There are 3 other families in this order, e.g., , Cannaceae, and . In this classification, the family Musaceae contains 6 genera. interesti~iglythese six genera alongwith plants of the families Zingiberaceae, Ca~i~iaceaeand Marantaceae were earlier classified together in Scita~nineaeby Bentham & Hooker.

In Takhtajan's classification, the family Musaceae is classified in subclass - Commelinidae, super order Zingiberanae, and Order Musales (also called ). There are 3 families in this order: i) Strelitziaceae (having Stralitzia and Ravenalu); ii) Musaceae (havi 11g Musa and Ensete as 2 distinct genera); and iii) Neliconiaceae (monogeneric with Heliconicr only). Lowiaceae (having Lowia with which Orchiduntlza has been merged) is classified in order Lowidales. Zi~igiberaceaeand are classified in order Zingiberales. Cannaceae and Marantaceae are now classified in order Cannales. Interestingly, Ensete separated out as a distinct genus by Takhtajan was included in tlie genus Musa by earlier taxonomists.

The description given above is for the family Musaceae as recognised by Engler and Prantl in its wide concept (as Musaceae sensu lato) and not in its restricted /. concept (as Musaceae sensu stricto). ( Economic Importance I. The largest genus Musa is the most important genus of this family. Many cultivated plants of this genus are important for tlie edible fruits, called tlie and the plantains. There are two views on the difference between the bananas and the plantains. According to "'The Flora of Hasan District, Karnataka, India" edited by C.J. Saldathha and D.H. Nicolson (Amerinsd Publislling Co. Pvt. Ltd., 1976) "In S. India, the starchy cooking Musa is called "banana"; and tlie sweet dessert type is called "plantain", On the other hand, S.L. Koclil~arin his book "Economic Botany in the Tropics" (Macmilla~lIndia Ltd., 1981, 1998) writes that ".. . .for the sake of convenience, the cultivated bananas are broadly classified in two groups; tlie dessert varieties and the cooking varieties. The fruits eaten as a dessert, without any cooking are called "bananas", while the more starcliy types with a less pleasant flavour and that need cooking before they can be consumed as a vegetable are called "plantains". From these two co~ilrastingviews, we only conclude that there are different types of fruits. Some are sweet (having more sugar) and can be eaten raw, while others are starchy and have to be cooked before they are eaten.

The cultivated bananas and plantains are the most widely grown of all tropical fruits. There are hundreds of varieties, which differ in size, colour and taste of the fruit. The vast majority of these cultivated varieties are Families of Angiosperms hybrids. They are mostly triploids and therefore, seeds do not develop. The mature fruits are consumed in various ways.

2. Besides the edible fruits, the genus Musa is also important for fibre. Musa textilis is cultivated for the "Manila hemp" or "Abaca fibre" which is obtained from the leaf sheaths which form the pseudostem. This is a very strong fibre and is used for marine ropes, twine and wrapping paper.

3. The stem of the cultivated bananas is also edible and is coolted as a vegetable. The leaves are used as plates and food is served on these leaves at many religious ceremonies.

4. Several species of Musa are cultivated as ornamentals. Ravenala is a beautiful palm-like plant. It is cultivated in gardens and parks for its symmetrical appearance. Strelitzia has a very beahtiful inflorescence with attractive brightly coloured spathe. , Heliconia metallica, and Mzisa nepalensis are also cultivated as ornamentals.

Points to Remember Monocot Families 23.3 LILIACEAE The Lily family Nomenclatural Type: . .

General Information The falnily Liliaceae includes about 260 genera and 4000 species. These are world wide in distribution. Some members are found in tlie north temperate regions. They commonly occur in tlie Himalayan region, in Scotland aid northern England, in North West Europe, in North America and in Japan. There are also genera wliicli are restricted in distribution or are endemic to South America and Australia. Some genera sliow wider distribution, occurring in tropical, subtropical and temperate regions of both liemisplieres. A few are found in the warmer parts of the Old World. In India, tliere are about 35 genera atid 230 species of this family. Tliey are found mainly in the Himalayan region, but tliere are some well known and very faniiliar members which are found tlirougl~outtlie country.

I11 B'entliam & Hooker's as well as E~igler& Prantl's classification, this large family is divided into as niany as 1 I sub families. In otlier syste~nsof classification, tlie tiumber of si~bfa~niliesis even larger. On tlie otlier hand, in Takhtajan's classification, Inally of the subfamilies arc treated as separate famn'ilies wliicli arc classified in different orders.

Interestingly, the family A~naryllidaceaeis quite similar in its characters with Liliaceae but differs in having an inferior ovary. They are classified as two separate families by most taxonomists. But tlie American taxononiist, Cronquist merged these two families and called it thc Liliacene. He did not give imporlance to the position of tlie ovary.

There is tlius diverse opinion about tlie family Liliaceae. In tlie following discussion, the suggestion of Bentliam and I-looker and Englcr & Prantl will be followed to know about the diversity in the falllily Liliaceae.

Field Recognition Rhizornatoi~sor bulbous herbs; or sliri~bsor tree-lilce woody plants; or woody climb el.^; or typical xerophytes; branches may be modified into flat-leaf-like cladodes; leaves simple; or reduced to scales or spines; or flesliy with water storing tissue and tliick cuticle; inflorescence of solitary terminal flowers, or a simple to bra~icliedraceme; or ~no~iocliasialcymes wliicli may be crowded into umbel-like heads; flowers bisexual, actinomorpliic, typically trimerous . liypogynous.

Morphological Diversity Tlie plants of tlie fanlily Liliaceae sliow diversity in their niospliology. Tlie majority of the ~nernbersof this family are lierbaccous perennials. Tliey may have a sympodial rliizome (Polygonatunz), monopodial () or a (e.g., Liliunz, , Alliun~,Tzdiya) as the perennating organ. Aerial leafy stems arise from the rhizome. In the bulbous fonns, the main aerial stem grows out and it may or may not bear leaves. This generally terminates in an inflorescence. After the clevelop~nentof the aerial stem, new are formed in the axils of the bulb scales for perennation. Someti~nesa is formed (e.g., ) at the base of the main axis, This modified stem persists it1 the soil even after the development of leaves and flowers. Families of Angiosperms Some members of this family are woody plants. They may have a tree-like habit (e.g., Dracaenn) with anamolous secondary growth. The stem increases in thickness by the formation of concentric rings of vascular bundles in the . is a large shrub or tree-like with a short and thick aerial stem. Typical xerophytic plants of the succulent type are colnmon in the genus . Some species of this genus also show an arborescent habit. In Yucca and Aloe also, there is anamolous secondary growth as in .

A much branched aerial stem with modified branches can be observed in and Aspmugus. Ruscus is shrub-like with the ultimate bra~lchesin the form of leaf-like structures called phylloclades. In , an underground rhizome produces slender lierbaceous or woody aerial branches. These may be erect or climbing and the ultimate branchlets are needle-like or narrow flattened cladodes. In , the plants are woody and clitnbing shrubs.

Leaf: The leaves show diverse morpl~ologicalforms and patterns of arrangetnent. In some plants, very few leaves are produced. They are generally basal and [nay be produced before or after flowering. In the bulbous herbs, the leaves may form a basal rosette and the main aerial stem may or may oot bear leaves. If this is leafy, then the leaves are alternate. The rhizomatous perennials have aerial stems which bear alternate leaves. In Di4ucaenathe leaves are either in a rossette or in two rows an the woody stem. Aloe has large thick fleshy leaves which store water. Tlle climbing Smilax has broad dicot-like alternatively arranged leaves. A pair of tendrils is present at the base of each leaf helping the Smilax plant to climb. Gloriosu, which is also a climbing plant has opposite leaves. It does not have tendrils at the base as in Smilax. Nowever, the leaf apex is produced into a tendril-like appendage which helps the plant to climb.

The leaves are arranged in whorls in Paris (Fig. 23.5), Trillizmt and other genera. In Asp~xragusand Ruscus (Fig. 23.5), the leaves are reduced to scales or spilles. Here, the modified branches (cladodes 01. phylloclades) serve the plant as photosynthetic organs. In general, the leaves are exstipulate, simple, linear and have parallel venation. In Drcacaena, the leaves are thick and leathery. In SiniZax the broad col.iaceous leaves show reticulate venation (Fig. 23.6).

In some plants, bulbils are formed in the axils of the leaves. These specialised bulbs serve as organs of .

C cladoda e4

Fig. 23.5: Purls q~iadrl/olia(n -d) a) . b) Flower. c) Ovnry, longisection. d) hither. e) Twig of Rliscus (R~iscusaculeafa). Monocot Families

Inflorescence: The no st common type of infloresccnce is racemose (Fig. 23.7). It may be a simple raceme or a panicle produced at tllc apical end of tlie aerial shoots. Sometimes tlie inflorescence is educed to a solitary teniiinal flower (e.g., Tzll@n,Lilizrnl). Tlie solitary flowcr may be axillary also (e.g., Glorio,rzr).Sometilnes the infloresccnce may be cynlose. In Henzerocallis, it is a mouocilasial cymc. Several such monochasial cymes with short internodes are crowded together to form an umbel-lilce or hencl- like colnplex inflorescence in Allizrtl~(Fig. 23.8), Agu~xmthzwand other genera.

, Flower: The flowers are bracteate but generally without bracteoles. So~iieti~nes(e.g., Lilizlnz) a single bracteole may cievelop. Tlie flowers are hisexual, actinomorphic, usually tri~nerousaid hypogynous. U~lisexual . flowers develop in ,'?"~ilaxancl Rz~,scus.Tlie flowers Inay bc telramel-ous in sollie genera. Families of Angiosperms The flowers are large, showy and fragrant attracting pollinators. Besides these general features, some genera also have special adaptations to ensure insect pollination. Nectar is secreted in septa1 glands between the carpels qnsuringthat come in contact with stigma and anthers. Alternatively, the flowers may exhibit protandry so that the anthers dehisce first and this is followed by the lengthening of the style and development of stigmatic papillae,

, Fig. 23.7: Aspl~odelustenui/oli~rs. a) Plant. b)Flower. c) Cnpsule with stnllc. d) Seed. Fig. 23.8: Allirrm cepn. R) Whole plnnt with bulb. b) L.S. bulb, c) Inflorea~ence.d) Single flower. e) Flower with part removed.

The most advanced type of adaptation is seen in Yucca (Fig. 23.9) where the stigmas are far above the anthers to allow self pollination. The pollination of these flowers is closely associated with the life cycle of a ~notllcalled Pronuba yuccasella. The flower provides the insect protection to its eggs which are laid in the ovary just below each ovule. In return, tlie insect pollinates the flower. The development of the insect larvae and the seeds proceeds together. The larvae- consulne solne of tlie developing seeds and come out tllrough the pericarp to Fanlilies of Angiosperms remain dormant as a cocoon in the soil. The adult moth emerges from the cocoon only when tlie plant flowers again to repeat tlie life-cycle.

Tlie perianth of the flower has two trimerous whorls. They are usually petaloid or, raleely,the outer wliorl is sepaloid. They are free or united and show imbricate or valvate aestivation.

Fig. 23.9: Yuccn . n) Plant (much reduced), b) Flower. c) Strmcns and pistil. d) Trnnsverse ~cction of ovary showing septnl glands between the three chambers. c) I'istil. f) Fruit. g) T.S. of fruit, which has bcconte six chambered by ingrow of middle wall of each carpel. h) Seeds, edge nnd surfnce views.

Androeciurn: There are generally G stamens in two trimerous whorls. Sometimes only 3 are fertile (e.g., Ruscus), and the other 3 are sterile. They may be reduced to or they may be absent. Rarely the number af stamens may be more than 6. The stamens are free or variously connate and are opposite the tepals. The anthers are bslsifixed and dithecous. They i~suallyshow introrse dehiscence,

Gynoecium: The gynoecium is tricarpeliary, syncarpaus and with a superior J ovary. The ovary is trilocular and shows slxile placentation. Sometimes the ovary is rnonolocular and has parietal placentation, The ovules are numerous and are generally present in two rows in each lacule, , c Nectaries are present in septa1 glands on the carpellary walls. There is a single style with a 3-lobed or with 3 distinct stigmas.

146 Fruit: Tlie fruit is usually a trilocular capsule wit11 loculicidal or septicidal Momocot Families deliiscence. Solnetimes it is a large berry (e.g., Smilax, Pogonatum, Asparagus). The seeds are large and numerous. They have a straiglit or curved embryo witli abundant fleshy or cartilaginous endosperm.

Diagnostic Features of the Family 1. Plants mostly rliizomatoiis or bulbous herbs, soinetimes woody or typical xerophytes. 2. Leaves simple, ge~ierallyalter~~ate, exstipulate and have parallel venation; sometimes reduced to scales or spines. 3. Infloresce~iceracemose or cy~noseor a solitary flower. 4. Flowers ebracteate, bisexual, actinomorphic, hypogynous and trimerous. 5. Flowers scented and with nectar. 6. Periantli in 2 wliorls, ge~ierallypetaloid. 7. A~idroecii~~nin 2 whorls, one so~netirnessterile or reduced to sta~ninodes,rarely absent; anthers basifixed, dithecous, introrse. 8. Gynoecium tricarpellary, syncarpous, ovary superior, placentatio~iaxile, ovules numerous. 9, Fruit a capsule or sometimes a berry. 10. Seeds large with abundant endosperm.

Systematic Position The family Liliaceae is classified by Bentliam & Hooker in Series Coronarieae. This series has 7 other families. The family (which has many morphological characters similar to Liliaceae) is classified separately in Epigynae. In Engler & Praiitl's classification, Liliaceae is classified in the order - Liliflorae. There are 9 falnilies in this order including Amaryllidaceae.

In both these systems of classification, tlie large family Liliaceae is divided into 11 sub families. Also, in both systems, Liliaceae is separated from Ainary llidaceae.

Takhtajan in liis system of classificatio~ibas re-organised the classification of this group of plants. As inariy as 8 subfamilies recognised in the earlier two systems of classificatio~ihave been recog~iisedas distinct families.

Interestingly, tliese families are classified in a different orders of subclass A . The family ~iliaceaeis also classified in this subclass and in super order Liliaiiae. It is classified in order wliiIe the family Amaryllidaceae is classified in order Amnryllidales. Thus, Takhtajan has followed Benthaln & Hooker as well as Engler & Praiitl in separating Liliaceae from Amaryllidaceae. There are also taxoriomists like Cronquist and others, who did not distinguish Liliaceae froin Ainaryllidaceae and united the two families as a single family called Lil iaceae,

Economic Importance 1. Food ylants cepa - . Tlie immature and mature bulbs are eaten raw or they may be cooked, fried or used in soups and sauces. Alternate leaves arise as rings on the very short flattened stem. These store food material. Famifie.: of Angiosperms AIIiurn sativa - . This is also widely cultivated and the specialised fleshy leaves are called "garlic cloves". These are used as a condiment for flavouring food. It is also used medicinally.

Asparagus officinalis - The young shoots atid fleshy are eaten as a vegetable or consumed in soups.

2. ~edicinalPlants A large ~iumberof plants of the Liliaceae are used in different medicines. These include , A, racernosus, Urginea indica, hyacinthiana, , GIoriosa superba, and Smilax species. Colchium autunznale yields an alkaloid colchicine wl~icllis used by cytogenetists to induce .

3. Fibres Fibres are obtained from terzax, Sansevieria species, Yucca filamenrosa.

4. Resin and Dracaena yield resin which is used in making vamisIi and sealing wax. indica yields a red dye from the flowers.

5. Ornamentals A large number of plants of this family are cultivated as ornamentals. The more well-known include species of: , Asparugus, , Dracaena, , Gloriosa, Hemerocallis, Lilium, Ruscus, Tulipa and Yucca. Monocot Families 23.4 ARECACEAE OR PALMAE The Palm family Nomenclatural Type: .

General Information TIiis distinctive family provides one of tlie tallest palm trees ( - 60 meters), tlie largest w~odyclimber (Calantzls up to 200 meters), the largest leaf (Raphia - 1 5 meters), one of the largest inflorescence ( - 7 meters), and the largest seed () in the plant Coiypha gigantic inflorescence kingdom. terminates the life of trees.

Tlie palms form a characteristic feature of tropical vegetation. They are wide spread in tropical and s~tbtropicalregions. Tliis family has about 200 genera mid 3000 species occurring in Asia, Africa and tropical America. Tlie palms may be conspicuous along coastlines or on oceanic islands. Some are well-known in cultivation. In India, there are about 28 genera and 90 species. Tlie most common ones are coco~iutpalm, , betel nut palm, toddy palm.

Field Recognition Tlie palms are large woody plants (Fig. 23.10); the stems are niostly unbranclied and colum~iar,rarely the stem may be reduced or it is thin and -like; tlie stern is generally covered with remains of old leaf slieatlis, or it is tlior~iy;tile large leaves are characteristic with either a palmate (fan-like) or pinnate (feather-like) shape; the leaves are present as a crown at tlie apex of tlie stem, The large paniculate inflorescence subtended by a spathe; flowers are small and unisexual, tlie fruit is a berry or a drupe.

Morphological Diversity Tlie ma-jorityof tlie palms are large trees with a tall woody stem. Tliis cylindrical stem grows erect and its diameter varies in different species. A single steni may attain a height up to 60 meters (e.g,, Ceraxylon). Interestingly, tliere is no secondary growtli, but sameti~nesthere is an increase in tlie diameter of older stems. Tliis increase is brought about in two ways; (a) There is an expansion of pare~icliy~natoustissue in wliich tlie vascular bundles are present; (b) Tliere is an increase in tlie cell cavity and wall tliick~iessof tlie sclerenchyma fitjres supporti~igtlie vascular bundles. The primary is short-lived and adventitious roots develop near the base of tlie stem. Several kinds of aerial roots i.e, stilt or prop root, spine root, a~idpneumatopliores are found in family. Tliese support the tall columnar stem.

Sometimes tlie stem is very sliort (e.g., acaz~lis, macrocarpa) or tlie plant may have a bushy habit. Tliis is due to tlie formation of ni~rnerouserect stems from horizontal suckers near the base of the main stem. In Calar~~us( or Cane), the stems are long, slender, and climb on surrounding vegetation. A single climbing stem may attain a length of about 200 meters. Families of Angiosperms

Fig. 23.10: Growth forms. a) Royslonea reglfl, l~rgetree palm with well-defined crownslinft. b) WwhingfonlafiIi/era, stem partially covered with persistent lnnrcent Icrves. c) lutescens,rnespitose habit, d) Calams sp., climber with cirrrte leaves.

Most palms are unbranched. Branching which is rab is observed in thebaica (dourn palm). Here the axillary bud grows into a branch like the main stem. Sometimes branching may occur due to injury of the ter~nillalbud (e.g., or wild date palm) (Fig. 23.11). 150 Monocot Families

Fig. 23.11: Plroerrixsylvestris, stem with scnrs from incisions on the lenfshentlrs for drlwi~~gsugnry snp.

Leaf: The leaf is the most characteristic feature of the palms. There are a few leaves generally forming a crown at tlie apex of tlie stem. They are often very large (e.g., A single leaf may be 15 meters long in Rcphia farinvera). Two types of leaves can be easily recognised in palms. Some palm's have palmate (fan- Fan palms have pnlmnte leaves. shaped) leaves while otliers have pirillate (feather-shaped) leaves. At tlie base of Feathcr palms have pinnote leaves tlie leaf is a sheath wllicli firmly fixes tlie leaf to tlie stem. The sheath has many bundles of fibres forming a dense mat around the younger leaves. These hay persist after tlie decay of the softer tissues. I11 , tlie sheath is a -like structure called oclirea.

A stout axis continues as tlie main axis of the large leaf. Tlie lamina is entire or dissected. I11 the fan palm, tlie laniina is entire in the bud and it is folded. As it opens and expands, tlie lamina may get torn along the folds to a greater or lesser degree. The folding of tlie lamina and tearing of the pinnae are also observed in the feather palmi.

Tlie leaves sl~owxerophytic characters. There is a thick glossy cuticle. As the leaf emerges, it is almost vertical to escape excessive radiation and transpiration. The leaf is rarely arranged perpendicular to the i~icidentrays of light.

The , leaves and stems may have thorns or recurved spikes.

Inflorescence: A few palms are , where a single large ter~ninal i~iflorescenceis produced after many years of vegetative growth. In Corypha un~braculifera(Talipot palm) the inflorescence is about 7 meters long. After the fruits are formed, tlie plant dies. Otlier palms have axillary infloresce~iceswhich are produced at regular intervals. In these palms, the plants do not die after flowering and fruiting.

The entire iriflorescence may be enclosed in a large spathe or each brancli of the large inflorescellce may have a spathe. Tlie inflorescence may be a simple or a compound spike or a large pahicle. The numerous flowers are sessile or sometimes embedded in the fleshy axis. In such cases the inflorescence is called a spadix (e.g., male i~iflorescenceof ), Both male and female flowers may be present on tlie same inflorescence. Generally, there are few female flowers towards the base of the inflorescence and numerous male flowers towards the apex. Sometimes the plants are dioecious (e.g., PIzoenix dactylifera or date palm, BorassusJIabellifer or palmyra palm). The inflorescence has a sweet smell (Fig. 23.12). - 151 Families of Angiosperms

Fig. 23.12: Borass~isjlabell~rmis.a) Hi~bit.b) Female inflorescence. c) Fruit cut transversely.

Flower: The flowers are small in con~parisonto tlie large inflorescence. They are typically trimerous, actinornorpliic, unisexual (rarely bisexual) and hypogynous. The perianth of the flower has 2 trilnerous wliorls wliicli are similar to each other. The outer whorl is generally smaller than the inner. Each is toi~gli,leatliery or fleshy. It is green to yellow or whitish and persistent. The aestivation is imbricate or valvate in the outer whorl. The inner whorl is valvate in tlie male flowers and imbricate in the female flowers.

There are generally six stamens, but sometimes there are only 3 in one wl~orl. Rarely, there are numerous stamens in a single flower. Filaments are free and ' short. The anthers are dithecous and show introrse dehiscence. Large amounts of

are produced and many palms are wind-pollinated. s

Gynoecium: The gynoecium is tricarpellary. It may be apocarpous (e.g., Phoenix) or syncarpous (e.g., Borassus, Aveca). Tlie ovary is superior and trilocular or unilocular. 'The placentation may be axile (trilocular) or parietal (unilocular). When the gynoecium is apocarpous, each carpel has a s,ingle ovule , on basal placenta. Sometimes 2 of the 3 carpels with their ovules abort during i development of the fruit, so that the mature fruit contains only one seed (e.g., Cocos nucgera or ). The style is generally absent and there are 3 sessile stigmas.

Fruit: The fruit is a fleshy berry (e.g., Phoenix dactylfera) or a fibrous drupe (e.g., Cocos nucifera) (Fig. 23.13). The fleshy pericarp of the fruit in' the date palm contains sugar and ellcloses a single cylindrical seed. In the fibrous drupe, the lnesocarp is made up of bundles of small fibres while the endocarp is hard and woody. In some palms (e.g., Calamus, or Sago palm:) the exocarp is covered with dry woody scales. The fruit varies greatly in size in d ifferent palms. The seed also shows diversity in shape and size corresporrding5 with tlie fruit, e.g., in Lodoicea maldiviccr (double coconut or coco-de-mer) thte fruit requires about 5 years to mature and contains a single large bilobed steed. Each fruit may weigh 13-22 kgs. noc cot Families

23.13: Arccnccnc: Cocos nrtcvcrn. a) Pnlm. b) Portion of leaf rnchis. c) Tip of lenf. d) lnflorcsccnce. e) Mnle flowcr and bud. f) Male flower opened. g) Fcmnlc flower. 11) Fcmnlc flowcr in L.S. i) Inflorescence with fruit. j) Ccrminnting fruit. k) Germinating fruits L.S. I) Ccrmil~rting fruit with mesocrrp removed. Families of Angioh

Fig. 23.14: Arecaceae: , a) Palm. b] Dnse of leaf, c) Tip of leaf. d) Inflorescence. e) Mnlc flower 1) Male flower in L.S. g) Female flower. h) Female flower in L.S. i) Fruit bunch. j) Fruit. k) Bruit in L.S. 154 The seed lias a large endosperm and a very small ern bryo. The endosperm may be Monocot Families soft forming a fleshy substance wliich stores oil and other food material (e.g., coconut). The endosperm rnay also be hard (e.g., date) or ru~ni~late(e.g., betel nut, Fig. 23.14) or it may be very thick and hard (e.g., vegetable ivory).

Diagnostic Features of the Family 1. Large woody plants generally with i~nbranchedcolumnar stem. 2. Stem covered with leaf sheaths. 3. Thorns or spines may be present on stem, petiole, or leaf. 4. Leaves very large, fan or feather shaped. 5. Inflorescence very large, subtended by sheaths, sweet smelling. 6. Plants monoecious or dioecious, flowers s~nall,~~nisexual. 7. Perianth not differentiated into calyx and corolla; tepals tough leathery or fleshy, persistent. 8. Stamens six, filaments free. 9. Tricarpellary gynoecium, ovary superior. 10. Fruit a berry or a drupe. 11. Seeds with abundant endosperm and small embryo. 12. Endosperm soft or hard.

Systematic Position Tlte family Palmae (Arecaceae) is classified in the ~no~locotyledo~lSeries - Calycinae by Be~itliam& Hooker. I11 Engler & Prantl's classification, tlie family is classified in the Order Principes. Takhtajan in his classification has classified the family Arecaceae in subclass - , super ordkr Arecanae, and Order .

Economic Importance The palms ljrovide a wide range of economic products. Many of them have ~nultipleuses, unlike other economic plants. They provide edible products, fats, waxes, fibres, raw material for furniti~reand many other articles. In many tropical areas, tlie palms serve as life supporting systems for mankind, providing several products for daily needs. The more important and well-known palm and some of their uses are listed here.

I. Cocos nucijera - Coconut palm. This is a feather palm. It is said to have more than 1000 uses because every part of the plant is useful. It provides food, beverage, oil, medicine, fibre, timber, thatching material, fans, mats, brushes, brooms, fuel, domestic utensils, decorative articles and many more. Jt lias been called "Kalpavriksl~'~or "tree of life" in ancient Indian literature. 2. Phoenix dactylifera - Date plam. The edible fruits are rich in sugar (60-70% of the fleshy pericarp is sugar). They may be eaten fresh, dried or used in bakery and confectionery. The stem and spathes may be tapped for obtaining palm wine or toddy. 3. Phoenix sylvestris - This is a fan palm which is tapped for its sap. The sap contains 12% sucrose and can be converted into jaggery and palm sugar. Tlie sap is also fermented to prepare an alcoh~licbeverage called toddy. For this, the inflorescence is tapped and up to 20 litres of sap can be obtained from a single plant, Tlie mature fruit is edible. The columnar stem is made up of ' durable which is used in various'ways. Fibres are obtained from the leaf stalks. I 4. Metroxylon rumphii, M sagus - Sago palms. These are feather palms. 1 , They are monoecious and monocarpic palms. A large terminal I inflorescence is produced when the palm is 10- 15 years old. The trunk of I this palm is cut before flowering and large quantities of starch are Families of Angiosperms removed. This starch is washed and dried to produce edible flour. Small granules called pearl sago are prepared from this flour. 5. Nypafiuticans - Nipa palm. This is an acaulescent feather palm. The palm i tapped for sugary sap which contains about 17% sucrose. It can be fermente to produce toddy or the toddy may be distilled to produce arrack. Vinegar is also produced from the sap. The sap may be evaporated to produce molasses like sugar called "gula malacca". 6. Arengapinnata - Sugar palm. This is a monoecious, donocarpic feather palm. A large quantity of starch is stored in the trunk. This is converted into sugar when the palm begins to flower. The peduncle of the male inflorescence is tapped to produce about 2.5 litres of sap per day. This tapping can be carried out for 2-3 months. The juice is boiled to produce sticky sugar or jaggery. Sago may be obtained if the stem is tapped before th onset of flowering. 7. wens - Fish-tail palm or Toddy palm. This is a monoecious, monocarpic feather palm. The inflorescence is tapped for the sap which is converted into toddy or sugar. 8. - Doum palm. This is a branched; dioecious bn palm. The sweet fleshy mesocarp of the fruit is edible. It is also used in medicine. The hard seeds are used as a substitute for vegetable ivory. The terminal may be tapped for toddy. 9. guineensis - Oil palm. This is a vely important fan palm. It provides Large scale cultivation of the oil the highest yield of vegetable oil per unit area for ally . Two distinct oils palm has been undertaken in several states of India by th called pal111oil and palm-kernel oil are obtained from this palm. Both are Department ofBiotechn&y. very important in the world trade in vegetable oils. Palm oil is obtained from This shall help the nation to become self-sufficient in edible the fleshy mesocarp of the fruit. The mesocarp contains 45-55% oil. This oil oil production. is light yellow to orange-red in colour. tt is edible and is also used industrially for the manufacture of soap, candles, railway axles, and other products.

Palm-kernel oil is obtained from the kernel or endosperm. It resembles coconut oil and is nearly colourless. It is edible and is used in confectionery and bakery products, and in ice-creams. It is also used in the manufacture of soaps and detergents. 10. cerifera - Camauba wax palm. This fan palm produces the most important vegetable wax which covers the leaves. The young leaves are cut and dried. The wax is removed from the surface and it is melted. It is very hard and has a high melting point. The wax is used in the manufacture of furniture, car and floor polishes: It is also used in the manufacture of paints, varnishes, carbon paper, gramophone records, ointments and lipstics. 1 1. Areca catechu - Betelnut palm. This is a fan palrri. The hard dried etidosperrr of the ripe and unripe seeds is widely used as a masticatory. It is chewed witk betelpepper leaf or alone. This habit of chewing betel is widespread and can cause cancer of the mouth. The betelnut is also commonly used in religious ceremonies and in medicine. 12. - Vegetable Ivory or Ivory nut palm. This is a . dioecious feather palm. The non-ruminate endosperm is made up of very hard and durable cellulose. It is used as a substitute for true ivory and is called vegetable ivory. It can be carved like true ivory. It is also used for making r chessmen, billiard balls, dice, buttons, and door knobs. It can be easily , coloured with dyes. ! 13. Lodoidea i~?nldivica= Lodoicea seychellarwn - Doilble Coconut or Coco-de- Monocot Families mer. This fan palm produces the largest seed in the plant kingdom. This is believed to be the palm on which the "Garuda" bird lived. The shells are used as vessels for collecting water, alms, etc. The leaves supply plaiting material for mats and other articles. 14. Calan~usrotang - Rattan or Cane palm. This is a climbing dioecious feather palm. The long stems are used for making cane furniture, walking sticks, polo sticks, ski sticks, swinging bridges, baskets and mats.

15. Ornamentalpnln?~- Many palms are grown for their elegant stur'cture and they are important ornamental plants in many gardens. A few of the more common ornamental palms are:

Roystoneu regin Cuban Royal palm or Bottle palm Cnryotn urens - Fish-tail palm Coryphn zm~bracz~l~era - Talipot palin Livisiona chinensis Chinese fan palm Arangupim7ata - Sugar palm Hyphuel~ethebaiclr - Egyptian Doum palm Lodoicea i~~nldivicaor - Coco-de-mer L. seychellarun? Families of Angiosperms 23.5 POACEAE OR GRAMINEAE

The Grass family Nomenclatural type: Boa

General Infol-mation l'he Poaceae constitute a natural and hotnogenous family of ~no~~ocotyledo~iousplants. The grasses are widely distributed tliroughout tlie world and they grow wherever plants can survive. This is one of tlie very large families of flowering plants having about 550 genera and 10,000 species. Tlie grasses can be found from tlie Equator to the poles, and from the sea level to the snowline on the mountains. They can occur on wet as well as dry places, in brakisli or fresh waters or even in deserts. Grasses prefer ope11 lands and are not common in dense forests. They may fonii dominant communities like the savanna, prairies, steppes and ~neadows.

Civilisations, developed when Inan learnt about agricultnre. The grasses were the first plants to be cultivated by man. These plants are quite distinct in tlieir characters and differ from tlie rest of the plant kingdom. Tliis interesting group of plants is represented in India by about 240 genera atid 1200 species, mid are foulid throughout the country. I Field Recognition l'he grasses are ~nostlyherbaceous plants with a fibrous root systeni; tlie aerial stems are terete and the internodes are generally liollaw; the leaves are alternate; each Ieaf consists of a slieatli, a lamina and a ligule. The lamina sliows parallel venation. Tlie infloresce~iceis made up of co~nplexspikelets; each l~assterile bracts arid paired fertile glumes, flowers are reduced and generally bisexual. The perianth is represented by lodicules. There are generally 3 stamens with versatile anthers. Tile gy~ioeciunagenerally has 2 feathery styles; the fruit is a or caryopsis wliicli you have already read in Unit I 1 of Block 3A.

Alll~oughthe grasses are distinct from otlier plants, they do sliow a superf?cial resemblance wit11 tlie sedges (members of tlie family ). These two groups of plants can be distinguished as follows: .

11 Box 23.1: Differences in Poaceae,and Cyperaceae.

Porreae Cyperncerre (grnsses)

I I, Sterns tercte is. circular in cross-section. 1 I. Stuns 2-sidul i.~..triangular in crass-section. I 2, Illternodes generally hollow. 2. Internodes solid.

Leaves altemato and 2-ranked. 3. Leaves 3-ranked. 1 3 I I I 4. Flowers in spiklcts and enclosed in pairs 4. Flowers in but in the mils of single of fertile glumes. fertile glunies. I II i ,, Morphological Diversity Most grasses are I~erbaceousplants, but a few (especially the ) are " woody. The herbaceous grasses tnay be annual or perennial. They have a well- developed fibrous and adventitious root system. In the perennial grasses, the lower internodes ale short and liulnerous branches arise from the lowermost leaf 158

1 axil. These branches or tillers grow erect giving a tufted appearance to the plant. Monocot Families In tlie ecbnomica~lyimportant grasses lilce (Fig. 23-16), the tillers increase the grain production per plant. This is due to tlie fact that each tiller termiiiates in an inflol-escence. Froin tlie base of tlie tillers, adve~ititiousroots arise to support tlie tufted grass (Fig. 23.1 5).

Fig. 23.15: Por rrnrrcta. n) I'ortion with panicles. b) Flowering culm. c) Spikelct. d) Lower involucrsl glunbe. c) lipper i~~volucrnlglume. f) Plornl glulne. g & 6') Outer and inner view of pnlcn rcspcctivcly. 11) Anthers, ovary and stigmas.

Tlie perenliial grasses lnay also liave an ~~ndergrou~ldrhizome. This is syrnpodial in nature atid is formed by the lower rlodes of the aerial branches. Erect aerial shoots arise fioiii this sy~iipoclialrliizome. Sometimes, a stoloniferous rootstock is for~iiedand aerial shoots arise from this rootstock. Tlie woocly ba~iiboosgrow in clumps. The clu~npsexpand coritinually by the formation of new slioots 011 the periphery. 'There is a big underground rl~izome from which the erect perennial woody sterns arise. A single barnboo stem may attain a height of 30 meters aiid a diameter of 25 cms. They are tlius tlie largest members of the grass family. Families of Angiosperms

Fig. 23.16: Tritic~rmnestlvum. a) Flowering plnnt. b) Cl~lrnwith Icrif. c, (I) Spikes, e) Spik~'Ict.f) A fl enclosed by Icrnrnn nnd pnlaea. g) Flower. 11) Cnryopsis r~~closedin glamcs. i) Cm'yopsi!

The aerial stems of the grasses are called cul~nsand they do not generally branch. In some tropical grasses and in bamboos, branching ofthe cu11n doe! occur. Each culm has well-marked nodes and internodes. The internodes towards the base are sliorter while those towards the apex are longer. Tile internodes are generally hollow because the parenchymatous (ground) tissue in which the vascular bundles are embeded, breaks down easily. But in nlays () (Fig. 23.1 81, Succhurttn?ofJiccinurztnt () (Fig. 23.17) and other grasses, the internodes are solid. Here the parenchymatous tissue does not break down.

The stems are terete (i.e. circular in cross-section). An intercalary ~neristema zone of special cells is present above each node in 1na11ygrasses. This enable elongation of the internode. It also enables the grass stem to become erect afi is bent dow~lwardsby external forces. Tlie culms remain rigid due to the I development of sclerenchymatous tissue beneath I.he and around tl vascular bundles. 1n many grasses (e.g., sugarcane), a root band containirlg ti root primordia or root initials of adventitious roots is also present just abova node.

160 Monocot Families

tic S

Flg. 23.17: Sncclrarrrm ojl7cinnrrim. n) Yoeng plrnt growing from sett. b) Portion of stem. c) Sett showing le early growth. d) Base of Iaminr. e) Infloresccncc. f) Portion of inflorescence. g) Spikeict. le each Leaf: In Poaceae, the leaves are alternate and arranged in 2 rows. (This is also called a disticllous arralige~nentor a 112 pliyllotaxy. (In the Cyperaceae, the leaves are 3 ranked showing a 113 pl~yllotaxy).The lower leaves may Families of Angiosperms appear crowded bccause of the shorter intelnodes. Each leaf has a basal sheath. The edges of this leaf sheath overlap on the opposite sides of tlie culm. They surround the internode and form a closed or open tube. This sheath protects the internode. The sheath is followed by tlie lamina or blade. I-lowever, in many bamboos and a few other grasses, a petiole separates tlie sheath from tlie blade. A special structure called ligule, is generally present at the junction of the sheatli and tlie blade. This is generally a membranous (sometimes a hairy) outgrowth at tlie apex of the sheath. The lamina or blade is usually long and narrow. It may be linear or linear-lanceolate and it generally tapers to a fine point. The margins of the blade may be entire, serrate or sharply toothed. TIie leaves sIiow parallel venation.

The stomata1 meclianis~nin the grasses is very distinct and cliaracte~*istic.The two guard,cells are elongated. They are bulbous at tlle two ends and straight in tlie middle. Tlie middle portior~of each guard cell has strong unevelily tliickenc walls. Tlie bulbous ends of tlie guard cells are thin walled. Increase or decrease pressure at the bulbous ends of the guard cclls result in opening or closing of tll stoniatal aperature.

In many xerophytic grasses, tlie leaf blades are ofie~ifolded or rolled up. Tliis folding or rolling up of tlie leaf is brought about by tlie parenchyma cells betwe tlie veins. When the atmosphere is moist, these parellcliylna cells are turgid and tlie blade is expanded. In dry conditions, these parenchyma cells become flacci, aitd tlie blade rolls up, When the blade is rolled up the stomata are completely enclosed. Tliis checks transpiration.

Inflorescence: The inflorescence is usually terminal on the culm and it is a complex structure. It consists of special units called spikelets. Several spikelets are arranged in dense (compact) to loose panicles, or in spilces or in racemes. In Triticunz aestivum (wlieat) (Fig. 23.16) and other grasses, the inflorescence is a spike of spikelets at the apex of each ti1 ler. Oryzn sativa () (Fig. 23,21), Saccharurn ofJicina~*z/m(sugarcane) (Fig. 23.17) and many other grasses ].lave a terminal panicle of spikelets. Tlie flowers are unisexual and tlie plalits are monoecious in Zea 1i7uy.s (maize) (Fig. 23.1 8). Here, tlie terminal Inale inflorescence is a panicle of spikelets. It is called a tassel. The female inflorescelice is a modified or specialised spike of spikelets and is called tile cob. The floral axis is tl~ickened.This female inflorescence appears in tlie axil of a leaf near tlie centre of tlie culm. It is acti~allyterminal and it is produced on a short coliipact lateral branch. Tliis special branch develops in the axil of the leaf. On a single maize platlt, there is only one male inflorescence but 2 or even 3 female illflorescences generally develop.

. Each spikelet consists of a condensed axis called the rachilla. At the base of this axis, there are one or two bract like structi~rescalled glumes. 'They do not bear any flowers. Their main function is to protect the developing flowers in the ; spikelet. Above these glumes there are I or more pairs of fertile glumes. A flower is enclosed in each pair of fertile glumes. ~acl~'pair of fertile glumes consists of an outer or lower fertile glume called lemma and an inner or upper ' glume called palea. The lemma is usually liiore prornineilt than the palea. Tlie lemma may or may not have a spine-like projection called the awn. Tliis may bd a terminal prolongation of the apex of the lemma. Sometimes, tlie awn is attached to the dorsal side of the lemma. The palea is usually menibraneous and: smaller than the lemma. The lemma is generally convex and the palea concwe j so that they make a compact pair enclosing tlie flower (Fig. 23.19). I This basic pattern of spikelet organisation is common throughout the family Monocot Families (Fig. 23.20). Each spikelet may have only one (e.g., , , Nordezlm, Oiyza) or 2 to many flowers (e.g.,Bronzus, , Eleusinz, Triticum, bamboos). The highly reduced flowers are also called florets.

Fig. 23.18: Zen niays. n) Plant b) Male infloresccncc, c) Male spiketclu. d) Mnlc spikclet In longitudinnl scction. c) MiiIc spikelet in transverse section, f) Female infloresccncc in longitudinnl section. g) Fcmrlc spikelct in longitetlinnl section (much enlarged). h) Ear. I) Caryopsiti. j) Caryopsl~ in lungit~ldinnl~cclion. Families of Angiosperms

C

I Fig. 23.19: Diagram of a spikelet of a grass as it would appear if the internodes bctwcen each set of organs were elongated. g') lower and g2) upper barren glume. P) fertile glurnr t~ndp) pwle of the second oldest Ilower. F') 1) a barren flower represented only by the axis and pale. Abovc it A single glume and the termination of the axis (rachilla) (a) of the spikclct.

Fig. 23.20: Diagram of a spikelet of a grass. The two barren glumes - g', lower, g', upper - embrace four flowers ofwhich 1 is tl~elower most and 4 the upper most. i Flowers: The flowers are very simple. They are small, inconspicuous, zygomo~rphic,hypogynous and usually bisexual. In some grasses the ,

flowers are unisexual (e.g., Zea mays) and someti~nestliere are both I bisexual and unisexual flowers in the same inflorescence (e.g., Agrostologist, is a taxono~nists , Erianthus, Paspalurn, Panicurn, ). A true perianth is who specialise in the study of absent, and according to some agrostologists the flowers are naked. I grasses However, each flower has generally 2 (sometimes 1 or 4) minute , membra~ieousor scaly structures called lodicules. They are present at the II base of tlie flower between the lemma and the palea. Many botanists I consider the lodicules to represent the periantl~of the flower. In a few I grasses (e.g., ) the lodicules are completely absent and the 1 flower is actually naked. The lodicules help to separate the lemma and the I palea so tliat tlie anthers and stigmas protrude out. Tliis is similar to the I opening of the flowers in other plants. The lodicules absorb ~noistureand ,

I swell. Pressure is tl1~1.sexerted at tlie base of the lemma and palea, Monocot Families separating tlie two laterally and exposi~igtlie reproductive organs. When tlie lodicules are absent, tlie lemma and palea do not separate laterally. In sucli grasses, tlie reproductive organs protrude out tlirough the apex of the fertile glumes.

Floweri~igoccurs a~i~iuallyin many of the perennial grasses, but in bamboos and sonie other grasses flowering is variable. Some bamboos flower and bear fruits at sliort i~itervalswithout dying. Otliers flower sporadically after intervals of a few to 40 years. There are also monocarpic bamboos wliicli produce a very large n~~mber of flowers only once in their lifetime. Such monocarpic ba~nboos'dieafier fruit formation (e.g., aniabilis, Oxytenanlhera abyssinica).

Most grasses have cliasmogamous flowers (those wliicli open and the reproductive organs protrude out through the le~n~naand palea). Tliese may be self or cross-pollinated. Some grasses Iiave cleistoga~nousflowers (closed flowers in which the reproductive organs are never exposed). These are always self-pol linated.

Androecium: Tliere are gelierally three stamens in a single whorl in the flower. I-Jowever in some grasses (e.g., Festuca, ), there is only one; stamen. In genera like Anthoxanthum and Coleanlhus, there are two stamens in tlie flower. Most bamboos, rice and Tn a few otlier grasses, there are two alternating tri~nerouswliorls of stamens in each flower. Rarely there may be more tlian six stamens.

Each stamen has a long delicate filament and a ditliecous anther. Tlle anthers are versatile and sl~owintrorse dehiscence. Each anther produces abundant fine granular and smootli pollen.

Gynoecium: Tliere are two views on tlie organisation of the gynoecium in the Poaceae. Some agt.ostologists believe that the gynoecium is monocarpellary. Others suggest tliat tlie gynoecium is either bi-or tri-carpellary and syncarpous. The superior ovary is always unilocular and has a single ovule on a basal placenta. There are usually two (sonietimes 1 or 3) styles each with a much-branched plumose (feathery) stigma. In Zea mays, the long silky stigmas are very prominent.

Fruit: Tlle fruit is very cliaracteristic in tl~isfamily. It is a dry indehiscent fruit called a caryopsis. This is a one-seeded fruit in which the pericarp (fruit wall) is conipletely fused with the testa (seed coat). The seed contains a small straight embryo 011 one side near tlle base. Tlie major part of the seed consists of the starchy endosperm. So~neti~iiesthe fruit is utricle (one-seeded hard dry indellisce~itfruit with a thin pericarp). Here the seed has a well- developed testa which is 1101 fused with the pericarp. The seed can be removed from the fruit (e.g., Bleznine coracana or finger ) (Fig. 23.22). In some bamboos, tlie pericarp is very hard forming a small nut-like fruit. I11 a few grasses (e.g., Hordeunz vulgare or ) the glumes are fused with tlie caryopsis. Families of Angiosperms

Fig. 23.21: Orylasativa. Rice. a) Base ofplant. b) Portion of stem with,eherth node. c) Base of lnn~in~with ligule and auricles. d) Emerging inflorescence. e) Portion of inflorescence. f) Open spikelet. g) Caryopsis.

Diagnostic Features of the Family 1. Plants generally herbaceous with a fibrous root system. 2. Tufted habit or with underground rhizome. 3. Aerial stems or culms are terete. 4. Internodes usually hollow. 5. Leaves distichous, with a basal sheath, a ligule and a long narrow lamina. 6. Venation parallel and stomata characteristic with buliform guard cells. 7. Inflorescence made up of spikelets having sterile and pairs of fertile glumes. 8. Flowers small, inconspicuous having a perianth of 0-3 minute membranceous Monocot Families lodicules. 9. Stamens 3 with versatile anthers. 10. Superior wary with single ovule and 2 styles with feathery stigmas. 11. Fruit a caryopsis. 12. Seed with small embryo and abundant starchy endosperm.

Fig. 23.22: Eleiislna corncarra. a) Flowering shoot, b) Base of plant. c) Spikelets. d) Lemma and palea in transverse section. e) Fruit. Families of Angiosperms Systematic Yositiora The family Poaceae is classified in - Glumaceae of the monocotyledons by Belitham and Hooker. This is the last series with Gramineae as the last family in this system of classification. The family Cyperaceae is also classified with Gramineae. In Engler & Prantl's classification, the fa~nilyGraminae is classified in Order Glumiflorae ofthe monocotyledons. This order also includes tlie family Cyperaceae. Takhtajan in his classification has classified tlie family Poaceae in subclass B - Commelinidae, super order Poanae and order - . In this system of classification, the family Cyperaceae is classified in Super Order Juncananae and Order - Cyperales of subclass Commelinidae.

Economic Importance The family Poaceae is economically the most important family of flowering plants. The are the most important grasses wliich have been used as staple diet by man since the dawn of civilization. Besides providing food for man, grasses are also used for feeding animals. They are important for production of alcoholic beverages and other products.

Some of the important and well known grasses used by man are listed here.

1. Cereals and There are six major cereals consumed by man: a) Triticurn aestivum - wheat b) sativa - rice c) Zea mays - maize d) Hordeunz vulpe- barley e) sativa - f) cereale -

Besides these, there are other edible grasses with small seeds. They are called millets. These include:

a) coracana - Fingermi l let, ragi b) tl phoides - pearl or bulrush ~nillet c) Sorghzrm vulgare - or jowar d) italica -1taliari millet e) Echinochloafiumentac~n- Japanese barnyard millet. f) Panicunl n~iliaceunz- Common mil let You have been provided detailed information about cereals and millets in Block 111 A, Unit 11.

2. Fodder Grasses The green herbage and dried fodder from grasses provide the basic food for man's domestic and many wild zn.nl~nals.Grass is the cheapest of all livestock feed. Naural grasslands or planeted pastures have different species of grasses. Some widely used fodder grasses include species of Digitaria, Erugrostis, Echinochlua, Loliunz, , , , , , Paspalunz, Soa, Seiaria, Sorghum and . Some of these . grasses may atso be grown for decorative purposes and in sports fields.

3. Sugar The genus Saccharurn has many economically important cultivated varieties. These are the most important source of cane sugar. Thus the sugarcane is one of the most valuable of the family Poaceae. A detailed account of this grass has been provided in Block I11 A, Unit 16. 4. Bamboos Monocot Families These tall arborescent grasses are classified in about 45 genera and more than 250 species. The largest number of species are found in the Indo- Malaysian region. 'There are numerous uses of bamboos. They lnay be used for constri~ctionpurposes. Houses, huts, rafts, bridges and other structures are made of bamboo. They are used for scaffolding, as poles or for making ladders, baskets, briisl~esand many more articles. Bamboo pulp is an in~pol-tantraw material in tlie paper industry. Besides, tliese uses, young shoots of some bamboo species are edible. Bamboo foliage is used as fodder for elephants and bamboos are also grown as wind-breakers and to check soil erosion.

'The bigger bamboos are obtained from species of , , Arznldinaria, , , , Oxytenanlhera alid other genera.

5. Essential Oils Lemon-grass oil is used in perfulnery and coslnetics as well as a flavourilag substance. It is obtained from the leaves of tlie grasses Cynlbopogon citratus and C,flexuosus. Otlier species of this genus are also irnportarit e.g., citronella grass - C. , girigergrass - C. caesius, roslaa grass - C. martini. They also yield essential oils.

Vetiveriazizaniozdes yields oil of vetiver (kllus). This is obtained from the roots. It is used in perfumery, cosmetics, soaps and for flavouring purposes. The roots are also woven into mats wliicl~when wet, cool and make the atmospl~erefragrant.

6. Miscellaneous Uses Several grasses are used for packing and thatching purposes and as building material. Fibres obtained from grasses are used for making ropes and as raw material for paper making. Stems of donax and karka are used for making lnusical pipes and other articles. The panicles of mminza are used for making brooms. Many grasses are widely used in soil conservation because tlieir fibrous root syste~nsact as efficient soil binders. This prevents soil erosion. Several grasses are important components of the landscape. These i~iclude golf courses sportsfields, lawns and other open spaces. Some grasses are also cultivated as ornamentals. Coix lachrynzu -job) ('job's tears or adlay) produces hard nut like fruits which show many variations in their size and colour. 'They are used as beeds for making necklaces. They are also used as poiiltry feed and for edible purposes. A beer like alcoholic beverage is also prepared from these fruits.

1 Assign the followi~~ggenera to tlieir respective families and mention one econolnic use of each. Gelrus Family Use a) Arundinnr ia b) Borassus C) Calarnzls d) Cyn~bopogon e) Dmcaena Jl Ravenala g) Strelitziu h) Yzjcca Families of Angiosperms 2. Subclass Liliidae in Taklltajan's.classification does not include: a) Arecaceae b) Liliaceae c) Musaceae d) Poaceae

3, List 3 families other than those mentioned above which are also classified in s~tbclassLiliidae.

4. Write the botanical name of the following plants. Common name Botanical name a) Birdofparadise b) Citronel la grass . c) Date palm d) Job'stears e) Traveller's tree f) Vegetable Ivory

5. a) What is meant by a monocarp'ic pla~it?

b) List three examples. i) i i) iii)

6. Define the following terms and name the family in which each has been described.

a) Culin ...... 1......

Family ......

Fatnily ...... :. Monocot k'amllies

Family ......

-- - a This unit defines the mo~iocotyledonsplants and describes in detail four selected families. These are Arecaceae, Liliaceae, Musaceae and Poaceae. . The nomenclatural type of each family, its size and distribution as well as infor~natiotlon the number of genera and species occurring in India have been mentioned. The diagnostic characters for recognising the plants of these families have been listed. Infor~natio~ion the systematic position of each family has been prbvided. This helps us to compare the different systems of plants classification: a The economically important plants are listed for each family to help us understand the value of plants for human welfare.

23.7 TERMINAL QUESTIONS 1. Mention the systems of classification in which the following~termsare used. ' Name one family which you have studied for each.

Term System of classification Family Arecidae Calycihae Poanae Coronarieae Glu~niflorae Liliiflorae Principes Zingiberales

2. a) Differentiate Family Musaceae sensu lato from Family Musaceae sensu stricto. b) Write a note on the systematic position of Family Musaceae in 3 systems of classification.

...... 11...(.1......

3. List the diagnostic features of Family Poaceae. Families of Angiosperms 4. Describe the vegetative and floral structures of: a) Family Arecaceae ......

b) Family Liliaceae ......

5. Write a note on the econolnic importanceiof: a) Family Musaceae

b) Family Poaceae

a) Based on your study of Block I11 (Economic Botany) and Block IV (Flowering Plants) and with the help of books in your study centre, prepare a list of the botanical names of all the plants (including Plant products) used by you and your family. Assign each plant to its botanical family. Recognise the most useful part of the plant and mention its use.

b) Collect 25 plants from your neighbourhood. Record the important cl~aracters of each plant (use Unit JV as a guide for recording this information). From these observations, you should be able to assign some of the plants to the families studied by you. Press the plants in newspapers to prepare herbariourn specimens. With the help of the botany teachers at your study centre, identifj; the plants you have collected. Write out a detailed report on this project.

23.8 ANSWERS Self-assessment Questions 1, Genus Family Use h a) Arundiharia Poaceae Bamboo for construction'etc. b) Borassus Arecaeae Palm sugar or jaggery or toddy. c) Calan~z~s Arecaceae Cane for furniture etc. d) Cyrnbopogon Poaceae Essential oils. e) Dracaenn Lil iaceae Resin, onlamental. f) Ravenala Musaceae Ornamental. g) Strelitzia Musaceae Ornamental 11) Yucca Lil iaceae Fibres, medicine, ornamental 2. a) Arecacae b) Musaceae c) Poaceae Monocot Families

3. List any three families from the Systematic Position of Family Liliaceae.

4. Common name Botanical name a) Bird of Paradise Strelitzia reginae b) Citronella grass Cynzbopogon nardus c) Date palm Phoenix dactylifera d) Job's tears Coix lacryma-jobi e) Traveller's Tree Ravenala madagascariensis f) Vegetable Ivory Phytelephas macrocarpa

5. a) A monocarpic plant is one wliicli flowers and fruits only once in its life itme. Flowering occurs after many years of vegetative growth and tlie plant dies after formation of fruits. b) i) Metroxylon rur~phii Sago palm i i) p innata Sugar palm i i i) Caryotu wens Fish tail palm iv) Arundinaria an~nbilis v) - abyssinica

6. a) Culm Aerial stem of a grass plant. It has well marked nodes and internodes. The internodes towards the base the shorter while those towards tlie apex are longer. Fa~nily - Poaceae b) Pliy ltoclade A modified stem usl~allyflattened and leaf like serving tlie plants as a pl~otosyntheticorgan. E.g., Ruscus. Family - Liliaceae c) Pseudostem A false stem, macle up of leaf sheaths which are rolled around one another, e.g., Musa. Fa~nily - Musaceae

Terminal Quest ions Term System of classification Family Arecidae Takhtajan Arecaceae Calycinae Bentharn & Hooker Arecaceae (Palmae) Poanae Takhtajan Poceae Coronarieae Bentliam & Hooker Liliaceae Glumi florae Engler & Prantl Poaceae Liliiflorae Engler & Prantl Liliaceae Principes Engler & Prantl Arecaceae Zingiberales Takhtajan Musaceae

2. a) Family Musaceae sensu lato refers to the definition ofthe family in a broad context. This includes other genera besides Musa.

Family Musaceae sensu strict0 refers to the definition of the family in a restricted context. This excludes several genera, but retains the genus Musa.

b) Refer to Section - Systematic Position of Musaceae.

3. Refer to Sectioli - Diagnostic features of Poaceae. Families of Angiosperms 4. a) Refer to Section - Morphological Diversity of Arecaceae.

b) Refer to Section -Morphological Diversity of Liliaceae.

5. a) Refer to Section - Economic Importance of Musaceae.

b) Refer to Section - Economic Impopance of Poaceae.